| Operation: | DEC |
| Function: | Decrement Register |
| Syntax: | DEC register |
| Instructions | OpCode | Bytes | Cycles | Flags |
| DEC A | 0x14 | 1 | 1 | None |
| DEC iram addr | 0x15 | 2 | 1 | None |
| DEC @R0 | 0x16 | 1 | 1 | None |
| DEC @R1 | 0x17 | 1 | 1 | None |
| DEC R0 | 0x18 | 1 | 1 | None |
| DEC R1 | 0x19 | 1 | 1 | None |
| DEC R2 | 0x1A | 1 | 1 | None |
| DEC R3 | 0x1B | 1 | 1 | None |
| DEC R4 | 0x1C | 1 | 1 | None |
| DEC R5 | 0x1D | 1 | 1 | None |
| DEC R6 | 0x1E | 1 | 1 | None |
| DEC R7 | 0x1F | 1 | 1 | None |
Description: DEC decrements the value of register by 1. If the initial value of register is 0, decrementing the value will cause it to reset to 255 (0xFF Hex). Note: The Carry Flag is NOT set when the value "rolls over" from 0 to 255.
See Also: INC, SUBB, Instruction Set